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Formation of intermediate-conductance calcium-activated potassium channels by interaction of Slack and Slo subunits

Abstract

Large-conductance calcium-activated potassium channels (maxi-K channels) have an essential role in the control of excitability and secretion. Only one gene Slo is known to encode maxi-K channels, which are sensitive to both membrane potential and intracellular calcium. We have isolated a potassium channel gene called Slack that is abundantly expressed in the nervous system. Slack channels rectify outwardly with a unitary conductance of about 25–65 pS and are inhibited by intracellular calcium. However, when Slack is co-expressed with Slo, channels with pharmacological properties and single-channel conductances that do not match either Slack or Slo are formed. The Slack/Slo channels have intermediate conductances of about 60–180 pS and are activated by cytoplasmic calcium. Our findings indicate that some intermediate-conductance channels in the nervous system may result from an interaction between Slack and Slo channel subunits.

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Figure 1: Amino-acid sequence alignment of Slack and the C. elegans f08b12.3 translation product with the human Slo (hslo), the Drosophila Slo (dslo) and the murine Slo3 (mslo3).
Figure 2: Proposed topology of Slack and its relationship to members of the Slo family.
Figure 3: Regional distribution of Slack expression.
Figure 4: Slack generates outwardly rectifying currents in Xenopus oocytes.
Figure 5: Slack generates outwardly rectifying currents in CHO cells.
Figure 6: The activity of Slack channels is decreased by cytoplasmic calcium.
Figure 7: Effects of NS-1619 and iberiotoxin indicate Slack and Slo subunits interact.
Figure 8: Examples of channel activity recorded in excised inside-out patches.

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References

  1. Nelson, M. T. et al. Relaxation of arterial smooth muscle by calcium sparks. Science 270, 633–637 (1995).

    Article  CAS  Google Scholar 

  2. Trautmann, A. & Marty, A. Activation of Ca-dependent K channels by carbamoylcholine in rat lacrimal glands. Proc. Natl Acad. Sci. USA 81, 611–615 (1984).

    Article  CAS  Google Scholar 

  3. Lingle, C. J., Solaro, C. R., Prakriya, M. & Ding, J. P. Calcium-activated potassium channels in adrenal chromaffin cells. Ion Channels 4, 261–301 (1996).

    Article  CAS  Google Scholar 

  4. Wang, W., Hebert, S. C. & Giebisch, G. Renal K+ channels: structure and function. Annu. Rev. Physiol. 59, 413– 36 (1997).

    Article  CAS  Google Scholar 

  5. Pacha, J., Frindt, G., Sackin, H. & Palmer, L. G. Apical maxi K channels in intercalated cells of CCT. Am. J. Physiol. 261, F696–F705 (1991).

    CAS  PubMed  Google Scholar 

  6. Storm, J. F. Potassium currents in hippocampal pyramidal cells. Prog. Brain Res. 83, 161–187 (1990).

    Article  CAS  Google Scholar 

  7. Lancaster, B., Nicoll, R. A. & Perkel, D. J. Calcium activates two types of potassium channels in rat hippocampal neurons in culture. J. Neurosci. 11, 23–30 (1991).

    Article  CAS  Google Scholar 

  8. Petersen, O. H. & Maruyama, Y. Calcium-activated potassium channels and their role in secretion. Nature 307, 693–696 (1984).

    Article  CAS  Google Scholar 

  9. Latorre, R., Oberhauser, A., Labarca, P. & Alvarez, O. Varieties of calcium-activated potassium channels Annu. Rev. Physiol. 51, 385–399 (1989).

    Article  CAS  Google Scholar 

  10. Robitaille, R., Garcia, M. L., Kaczorowski, G. J. & Charlton, M. P. Functional colocalization of calcium and calcium-gated potassium channels in control of transmitter release. Neuron 11, 645–655 (1993).

    Article  CAS  Google Scholar 

  11. Reinhart, P. H., Chung, S., Martin, B. L., Brautigan, D. L. & Levitan, I. B. Modulation of calcium-activated potassium channels from rat brain by protein kinase A and phosphatase 2A. J. Neurosci. 11, 1627–1635 (1991).

    Article  CAS  Google Scholar 

  12. Chung, S. K., Reinhart, P. H., Martin, B. L., Brautigan, D. & Levitan, I. B. Protein kinase activity closely associated with a reconstituted calcium-activated potassium channel. Science 253, 560–562 (1991).

    Article  CAS  Google Scholar 

  13. Sansom, S. C., Stockand, J. D., Hall, D. & Williams, B. Regulation of large calcium-activated potassium channels by protein phosphatase 2A. J. Biol. Chem. 272, 9902– 9906 (1997).

    Article  CAS  Google Scholar 

  14. Dworetzky, S. I. et al. Phenotypic alteration of a human BK (hSlo) channel by hSlobeta subunit coexpression: Changes in blocker sensitivity, activation/relaxation and inactivation kinetics, and protein kinase A modulation. J. Neurosci. 16, 4543–4550 (1996).

    Article  CAS  Google Scholar 

  15. McManus, O. B., et al. Functional role of the beta subunit of high conductance calcium-activated potassium channels. Neuron 14, 645– 650 (1995).

    Article  CAS  Google Scholar 

  16. Wallner, M. et al. Characterization of and modulation by a beta-subunit of a human maxi KCa channel cloned from myometrium. Receptors Channels 3, 185–199 (1995).

    CAS  PubMed  Google Scholar 

  17. Schopperle, W. M. et al. Slob, a novel protein that interacts with the Slowpoke calcium-dependent potassium channel. Neuron 20, 565– 573 (1998).

    Article  CAS  Google Scholar 

  18. Xia, X. M., Hirschberg, B., Smolik, S., Forte, M. & Adelman, J. P. dSLo interacting protein 1, a novel protein that interacts with large-conductance calcium-activated potassium channels. J. Neurosci. 18, 2360– 2369 (1998).

    Article  CAS  Google Scholar 

  19. Atkinson, N. S., Robertson, G. A. & Ganetzky, B. A component of calcium-activated potassium channels encoded by the Drosophila slo locus. Science 253, 551–555 (1991).

    Article  CAS  Google Scholar 

  20. Adelman, J. P. et al. Calcium-activated potassium channels expressed from cloned complementary DNAs. Neuron 9, 206– 216 (1992).

    Article  Google Scholar 

  21. Tseng-Crank, J. et al. Cloning, expression and distribution of functionally distinct Ca2+-activated K+ channel isoforms from human brain. Neuron 13, 1315– 1330 (1994).

    Article  CAS  Google Scholar 

  22. Dworetzky, S. I., Trojnacki, J. T. & Gribkoff, V. K. Cloning and expression of a human large-conductance calcium-activated potassium channel. Mol. Brain Res. 27, 189–193 (1994).

    Article  CAS  Google Scholar 

  23. Butler, A., Tsunoda, S., McCobb, D. P., Wei, A. & Salkoff, L. mSlo, a complex gene encoding "maxi" calcium-activated potassium channels. Science 261, 221–224 (1993).

    Article  CAS  Google Scholar 

  24. McCobb, D. P. et al. A human calcium-activated potassium channel gene expressed in vascular smooth muscle. Am. J. Physiol. 267, H767–H777 (1995).

    Google Scholar 

  25. Saito, M., Nelson, C., Salkoff, L. & Lingle, C. J. A cysteine-rich domain defined by a novel exon in a slo variant in rat adrenal chromaffin cells and PC12 cells. J. Biol. Chem. 272, 11710–11717 (1997).

    Article  CAS  Google Scholar 

  26. Navaratnam, D. S., Bell, T. J., Tu, T. D., Cohen, E. L. & Oberholtzer, J. C. Differential distribution of Ca2+-activated K+ channel splice variants among hair cells along the tonotopic axis of the chick cochlea. Neuron 19, 1077 –1085 (1997).

    Article  CAS  Google Scholar 

  27. Rosenblatt, K. P., Sun, Z. P., Heller, S. & Hudspeth, A. J. Distribution of Ca2+-activated K+ channel isoforms along the tonotopic gradient of the chicken's cochlea. Neuron 19, 1061–1075 (1997).

    Article  CAS  Google Scholar 

  28. Jones, E. M., Laus, C. & Fettiplace, R. Identification of Ca2+-activated K+ channel splice variants and their distribution in the turtle cochlea. Proc. R. Soc. Lond. 265, F>685–692 (1998).

  29. Morita, T., Hanaoka, K., Morales, M. M., Montrose-Rafizadeh, C. & Guggino, W. B. Cloning and characterization of maxi K+ channel alpha-subunit in rabbit kidney. Am. J. Physiol. 273, F615– F624 (1997).

    CAS  PubMed  Google Scholar 

  30. Dryer, S. E., Duorado, M. M. & Wisgirda, M. E. Characteristics of multiple Ca2+-activated K+ chanels in acutely dissocated ciliary ganglion neurons. J. Physiol. 443, 601–627 (1991).

    Article  CAS  Google Scholar 

  31. Toro, L., Vaca, L. & Stefani, E. Calcium-activated potassium channels from coronary smooth muscle reconstituted in lipid bilayers. Am. J. Physiol. 260, H1779–H1789 (1991).

    CAS  PubMed  Google Scholar 

  32. Sakaba, T., Ishikane, H. & Tachibana, M. Ca2+-activated K+ current at presynaptic terminals of goldfish retinal bipolar cells. Neurosci. Res. 27, 219–228 (1997).

    Article  CAS  Google Scholar 

  33. Farley, J. & Rudy, B. Multiple types of voltage-dependent Ca2+-activated K+ channels of large conductance in rat brain synaptosomal membranes. Biophys. J. 53 , 919–934 (1988).

    Article  CAS  Google Scholar 

  34. Kang, J., Huguenard, J. R. & Prince, D. A. Two types of BK channels in immature rat neocortical pyramidal neurons. J. Neurophysiol. 76, 4194–4197 (1996).

    Article  CAS  Google Scholar 

  35. Reinhart, P. H., Chung, S. & Levitan, I. B. A family of calcium-dependent potassium channels from rat brain. Neuron 2, 1031– 1041 (1989).

    Article  CAS  Google Scholar 

  36. Wei, A, Jegla, T. & Salkoff, L. Eight potassium channel familes revealed by the C. elegans genome project. Neuropharmacology 35 , 805–829 (1996).

    Article  CAS  Google Scholar 

  37. Heginbotham, L., Lu, Z., Abramson, T. & MacKinnon, R. Mutations in the K+ channel signature sequence. Biophys.J. 66, 1061–1067 (1994) .

    Article  CAS  Google Scholar 

  38. Schreiber, M. et al. Slo3, a novel pH-sensitive K+ channel from mammalian spermatocytes. J. Biol. Chem. 273, 3509–3516 (1998).

    Article  CAS  Google Scholar 

  39. Papazian, D.M. & Bezanilla, F. How does an ion channel sense voltage? News Physiol. Sci. 12, 203- 210 (1997).

    CAS  Google Scholar 

  40. Wallner, M., Meera, P. & Toro, L. Determinant for beta-subunit regulation in high-conductance voltage-activated and Ca2+-sensitive K+ channels: An additional transmembrane region at the N terminus. Proc. Natl Acad. Sci. USA 93, 14922–14927 (1996).

    Article  CAS  Google Scholar 

  41. Meera, P., Wallner, M., Song, M. & Toro, L. Large conductance voltage- and calcium-dependent K+ channel, a distinct member of voltage-dependent ion channels with seven N-terminal transmembrane segments (S0-S6), an extracellular N terminus, and an intracellular (S9-S10) C terminus. Proc. Natl Acad. Sci. USA 94, 14066– 14071 (1997).

    Article  CAS  Google Scholar 

  42. Ponting, C. P., Phillips, C., Davies, K. E. & Blake, D. J. PDZ domains: targeting signalling molecules to sub-membranous sites. Bioessays 19, 469–479 (1997).

    Article  CAS  Google Scholar 

  43. Hanner,M. et al. The beta subunit of the high-conductance calcium-activated potassium channel contributes to the high-affinity receptor for charybdotoxin. Proc. Natl Acad. Sci. USA 94, 2853– 2858 (1997).

    Article  CAS  Google Scholar 

  44. Mienville, J. M. & Barker, J. L. Immature properties of large-conductance calcium-activated potassium channels in rat neuroepithelium. Pflugers Arch. 431, 763– 770 (1996).

    Article  CAS  Google Scholar 

  45. Hirsch, J. R. & Schlatter, E. Ca2+-dependent K+ channels in the cortical collecting duct of rat. Wien. Klin. Wochenschr. 109, 485–488 (1997).

    CAS  PubMed  Google Scholar 

  46. Kanyicska, B., Freeman, M. E. & Dryer, S. E. Endothelin activates large-conductance K+ channels in rat lactotrophs: reversal by long-term exposure to dopamine agonist. Endocrinology 138, 3141– 3153 (1997).

    Article  CAS  Google Scholar 

  47. Knaus, H.-G. et al. Distribution of high-conductance Ca2+-activated K+ channels in rat brain: targeting to axons and nerve terminals. J. Neurosci. 16, 955–963 (1996).

    Article  CAS  Google Scholar 

  48. Chang, C. P., Dworetzky, S. I., Wang, J. & Goldstein, M. E. rential expression of the alpha and beta subunits of the large-conductance calcium-activated potassium channel: implication for channel diversity. Mol. Brain Res. 45, 33–40 (1997).

    Article  CAS  Google Scholar 

  49. Altschul, S. F., Gish, W., Miller, W., Myers, E.W. & Lipman, D. J. Basic local alignment search tool. J. Mol. Biol 215, 403–410 (1990).

    Article  CAS  Google Scholar 

  50. Joiner, W. J., Wang, L.-Y., Tang, M. & Kaczmarek, L.K. hSK4, a member of a novel subfamily of calcium-activated potassium channels. Proc. Natl Acad. Sci. USA 94, 11013– 11018 (1997).

    Article  CAS  Google Scholar 

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Acknowledgements

We thank J. Boulter for his gift of the rat brain cDNA library. We also thank J. Trojnacki and J. McCaughern-Carucci for technical assistance. These studies were supported by an NIH grant to L.K.K.

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Correspondence to Leonard K. Kaczmarek.

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Joiner, W., Tang, M., Wang, LY. et al. Formation of intermediate-conductance calcium-activated potassium channels by interaction of Slack and Slo subunits. Nat Neurosci 1, 462–469 (1998). https://doi.org/10.1038/2176

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